Lens system with optical actuator

ABSTRACT

Compact lens systems that may be used in small form factor cameras. The lens system may include a master lens with two or more lens elements arranged along an optical axis and having refractive power, and an optical actuator located on the object side of the master lens that may provide autofocus (AF) and/or optical image stabilization (OIS) functionality for the camera. An aperture stop for the camera may be included in the optical actuator, for example between a substrate and a flexible optical element of the optical actuator. Including the aperture stop in the optical actuator rather than in the lens stack may allow the optical actuator to be smaller in the X-Y dimensions (perpendicular to the optical (Z) axis) than it would be in a similar camera with the aperture stop located in the lens stack.

This application is a 371 of PCT Application No. PCT/US2017/045978,filed Aug. 8, 2017, which claims benefit of priority to U.S. ProvisionalPatent Application No. 62/372,690, filed Aug. 9, 2016. The aboveapplications are incorporated herein by reference. To the extent thatany material in the incorporated application conflicts with materialexpressly set forth herein, the material expressly set forth hereincontrols.

BACKGROUND Technical Field

This disclosure relates generally to camera lens systems, and morespecifically to high-resolution, small form factor camera systems andlens systems.

Description of the Related Art

The advent of small, mobile multipurpose devices such as smartphones andtablet or pad devices has resulted in a need for high-resolution, smallform factor cameras for integration in the devices. However, due tolimitations of conventional camera technology, conventional smallcameras used in such devices tend to capture images at lower resolutionsand/or with lower image quality than can be achieved with larger, higherquality cameras. Achieving higher resolution with small package sizecameras generally requires use of a photosensor with small pixel sizeand a good, compact imaging lens system. Advances in technology haveachieved reduction of the pixel size in photosensors. However, asphotosensors become more compact and powerful, demand for compactimaging lens system with improved imaging quality performance hasincreased.

Some small form factor cameras may incorporate an autofocus (AF)mechanism whereby the object focal distance can be adjusted to focus anobject plane or field in front of the camera at an image plane to becaptured by an image sensor (also referred to herein as a photosensor).In some such autofocus mechanisms, the optical lens is moved as a singlerigid body along the optical axis (referred to as the Z axis) of thecamera to refocus the camera. In addition, high image quality is easierto achieve in small form factor cameras if lens motion along the opticalaxis is accompanied by minimal parasitic motion in the other degrees offreedom, for example on the X and Y axes orthogonal to the optical (Z)axis of the camera. Thus, some small form factor cameras that includeautofocus mechanisms may also incorporate optical image stabilization(OIS) mechanisms that may sense and react to external excitation ordisturbance by adjusting location of the optical lens on the X and/or Yaxis in an attempt to compensate for unwanted motion of the lens.

SUMMARY OF EMBODIMENTS

Embodiments of the present disclosure may provide a camera in a smallpackage size, referred to as a small format factor camera. A smallformat factor camera is described that includes a photosensor and acompact lens system. Embodiments of the compact lens system include anoptical actuator element, for example an optical microelectromechanicalsystem (MEMS), and one or more refractive lens elements, referred to asa lens stack or master lens. The optical actuator may be located on theobject side of the lens stack in front of a first lens of the stack,while the photosensor is located on the image side of the lens stack.The optical actuator may include, but is not limited to, a substrate atleast partially composed of a clear material or substance (e.g., a clearglass or plastic substrate), a flexible optical element (e.g., aflexible lens), and an actuator component that is configured to changethe shape of the flexible optical element to provide adaptive opticalfunctionality for the camera. The optical functionality provided by theoptical actuator may include autofocus (AF) functionality and/or opticalimage stabilization (OIS) functionality, for example. The opticalactuator may also be referred to as an SSAF (Solid-State Auto-Focus)and/or SSOIS (Solid-State Optical Image Stabilization) component ormodule. By using SSAF and/or SSOIS technology to provide AF and/or OISfunctionality in small form factor cameras as described herein, there isno longer a requirement to physically move the lens barrel with respectto the photosensor to achieve AF and/or OIS functionality. This has asignificant impact on the X-Y size of the camera system by reducing thesize of the camera in the X-Y dimensions.

In embodiments, an aperture stop for the camera may be included in theoptical actuator, for example between the substrate and the flexibleoptical element of the optical actuator. Including the aperture stop inthe optical actuator rather than in the lens stack may allow the opticalactuator to be smaller in the X-Y dimensions (perpendicular to theoptical (Z) axis) than it would be in a similar camera with the aperturestop located in the lens stack. For example, the optical actuator may be20-30% smaller. This may allow the X-Y dimensions of the camera to bereduced when compared to a similar camera with the aperture stop locatedin the lens stack, and may also allow the X-Y dimensions of a coverwindow for the camera to be reduced. In addition, the smaller opticalactuator may be less expensive to manufacture. Shapes, spacing, and/orsizes of the lens elements in the lens stack may be selected to accountfor the location of the aperture stop in front of the lens stack in theoptical actuator, and for the size of the entrance pupil of the aperturestop. For example, the X-Y dimensions of one or more of the lenselements in the lens stack (e.g., the first three lens elements from theobject side of the camera) may be increased according to the locationand size of the aperture stop in the optical actuator so that the lightrays passing through the aperture stop are correctly refracted throughthe lens elements in the lens stack to form an image at an image planeon the photosensor. The lens elements in the lens stack may be selectedand arranged such that mechanical vignetting of the lens system isreduced or eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate motion of an optics component within anexample actuator module that provides mechanical autofocus (AF) and/oroptical image stabilization (OIS) functionality for a camera.

FIG. 2 illustrates a lens module with a fixed master lens and an opticalactuator component that provides AF and/or OIS functionality for thecamera, according to some embodiments.

FIG. 3 is a cross-sectional illustration of a camera including a lenssystem with a fixed master lens and an optical actuator component inwhich the aperture stop for the camera is located within the lensbarrel, according to some embodiments.

FIG. 4 is a cross-sectional illustration of a camera including a lenssystem with a fixed master lens and an optical actuator component inwhich the aperture stop for the camera is located in the opticalactuator component, according to some embodiments.

FIG. 5 is a cross-sectional illustration of a camera lens assembly ormodule that includes an optical actuator component with integratedaperture stop, a fixed master lens, and an optional infrared (IR)filter, according to some embodiments.

FIGS. 6A and 6B illustrate an example optical actuator component,according to some embodiments.

FIGS. 7A and 7B illustrate an example optical actuator component thatincludes an aperture stop, according to some embodiments.

FIG. 8 is a flowchart of a method for capturing images using a camera asillustrated in FIG. 4, according to some embodiments.

FIG. 9A shows components of an example small form factor camera thatincludes a camera lens assembly as illustrated in FIG. 5 and illustratesa method for assembling the camera, according to some embodiments.

FIG. 9B shows an example small form factor camera that includes a cameralens assembly as illustrated in FIG. 5 and provides example dimensionsand optical characteristics for the camera, according to someembodiments.

FIG. 10 illustrates an example computer system that may be used inembodiments.

This specification includes references to “one embodiment” or “anembodiment.” The appearances of the phrases “in one embodiment” or “inan embodiment” do not necessarily refer to the same embodiment.Particular features, structures, or characteristics may be combined inany suitable manner consistent with this disclosure.

“Comprising.” This term is open-ended. As used in the appended claims,this term does not foreclose additional structure or steps. Consider aclaim that recites: “An apparatus comprising one or more processor units. . . ”. Such a claim does not foreclose the apparatus from includingadditional components (e.g., a network interface unit, graphicscircuitry, etc.).

“Configured To.” Various units, circuits, or other components may bedescribed or claimed as “configured to” perform a task or tasks. In suchcontexts, “configured to” is used to connote structure by indicatingthat the units/circuits/components include structure (e.g., circuitry)that performs those task or tasks during operation. As such, theunit/circuit/component can be said to be configured to perform the taskeven when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invoke 35U.S.C. § 112, sixth paragraph, for that unit/circuit/component.Additionally, “configured to” can include generic structure (e.g.,generic circuitry) that is manipulated by software and/or firmware(e.g., an FPGA or a general-purpose processor executing software) tooperate in manner that is capable of performing the task(s) at issue.“Configure to” may also include adapting a manufacturing process (e.g.,a semiconductor fabrication facility) to fabricate devices (e.g.,integrated circuits) that are adapted to implement or perform one ormore tasks.

“First,” “Second,” etc. As used herein, these terms are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.). For example, a buffer circuitmay be described herein as performing write operations for “first” and“second” values. The terms “first” and “second” do not necessarily implythat the first value must be written before the second value.

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While in this case, B is a factor that affects the determination of A,such a phrase does not foreclose the determination of A from also beingbased on C. In other instances, A may be determined based solely on B.

DETAILED DESCRIPTION

Embodiments of a compact lens system, which may also be referred to as alens module, are described that may include an optical actuator, forexample an optical microelectromechanical system (MEMS), and one or morerefractive lens elements, referred to as a lens stack, lens barrel, ormaster lens. Embodiments of the compact lens system may be used incameras with a small package size, referred to as small format factorcameras. Embodiments of small format factor cameras are described thatinclude, but are not limited to, a photosensor and embodiments of thecompact lens system.

In embodiments of the compact lens system, an optical actuator may belocated on the object side of the lens stack in front of a first lens ofthe stack, while the photosensor is located on the image side of thelens stack. The optical actuator may include, but is not limited to, asubstrate (e.g., a clear glass or plastic substrate), a flexible opticalelement (e.g., a flexible lens), and an actuator component that isconfigured to dynamically change the shape of the flexible opticalelement to provide adaptive optical functionality for the camera. Theoptical functionality provided by the optical actuator may includeautofocus (AF) functionality and/or optical image stabilization (OIS)functionality, for example. The optical actuator may also be referred toas an SSAF (Solid-State Auto-Focus) and/or SSOIS (Solid-State OpticalImage Stabilization) component or module. While embodiments aregenerally described in which the optical actuator provide AF and/or OISfunctionality for the camera, other optical functionalities, such aszoom functionality, may be provided by the optical actuator in someembodiments.

Typically, to achieve AF and/or OIS functionality in small form factorcameras, mechanical solutions, such as VCM (voice coil motor) technologythat moves the lens module in relation to the image plane in the Z(optical axis) direction for AF and either by tilting or displacing thelens module in the X and Y (perpendicular to the Z axis) directions forOIS, have been used, for example as illustrated in FIGS. 1A and 1B.These mechanical solutions require that the lens barrel be assembledinto a holder, and the overall system X-Y size is thus defined by thesize of the holder. Thus, the system has an X-Y size that is defined bythe holder X-Y size, the holder size is defined by the lens barrel X-Ysize, which in turn is defined by the lens element X-Y sizes. This makesfor a relatively large X-Y footprint for the camera. By using SSAFand/or SSOIS technology to provide AF and/or OIS functionality in thesmall form factor cameras described herein, there is no longer arequirement to move the lens barrel with respect to the image plane. Thelens barrel can be fixed directly to the photosensor and therefore theholder is redundant and is removed. This has a significant impact on theX-Y size of the camera system by reducing the size of the camera in theX-Y dimensions.

The addition of the optical actuator that provides SSAF and/or SSOISfunctionality to the lens barrel may increase the Z dimension of thelens assembly. However, as the displacement of the lens barrel is nolonger required to achieve AF functionality, a much smaller nominaldistance between the lens barrel and the camera system cover window canbe achieved in embodiments. This offsets the majority or all of the netincrease in the Z dimension due to the addition of the optical actuator.

In conventional cameras, an aperture stop for the camera may be includedin the lens stack, for example at the first lens element in the stack.In at least some embodiments of the compact lens system as describedherein, rather than including an aperture stop in the lens stack, forexample at the first lens element in the stack, an aperture stop may beincluded in the optical actuator, for example between the substrate andthe flexible optical element of the optical actuator. Including theaperture stop in the optical actuator rather than in the lens stack mayallow the optical actuator to be smaller in the X-Y dimensions(perpendicular to the optical (Z) axis) than it would be in a similarcamera with the aperture stop located in the lens stack. For example,the optical actuator may be 20-30% smaller. This may allow the X-Ydimensions of the camera to be reduced when compared to a similar camerawith the aperture stop located in the lens stack, and may also allow theX-Y dimensions of a cover window for the camera to be reduced. Inaddition, the smaller optical actuator may be less expensive tomanufacture.

Shapes, spacing, and/or sizes of the lens elements in the master lensmay be selected to account for the location of the aperture stop infront of the lens stack in the optical actuator. For example, the X-Ydimensions of one or more of the lens elements in the master lens (e.g.,the first three lens elements on the object size of the master lens) maybe increased according to the location of the aperture stop in theoptical actuator so that the light rays passing through the aperturestop are correctly refracted through the lens elements in the lens stackto form an image at an image plane on or proximate to the photosensor.The lens elements in the lens stack may be selected and arranged suchthat mechanical vignetting is reduced or eliminated in embodiments ofthe camera in which the aperture stop is included in the opticalactuator. While it would be possible to maintain the aperture stop atthe first lens element of the master lens and to add a field stop in theoptical actuator, this arrangement may significantly affect the relativeillumination of the system due to mechanical vignetting.

Embodiments of the small format factor camera as described herein may beimplemented in a small package size while still capturing sharp,high-resolution images, making embodiments of the camera suitable foruse in small and/or mobile multipurpose devices such as cell phones,smartphones, pad or tablet computing devices, laptop, netbook, notebook,subnotebook, and ultrabook computers, and so on. However, note thataspects of the camera (e.g., the lens system and photosensor) may bescaled up or down to provide cameras with larger or smaller packagesizes. In addition, embodiments of the camera system may be implementedas stand-alone digital cameras. In addition to still (single framecapture) camera applications, embodiments of the camera system may beadapted for use in video camera applications. In some embodiments, acamera as described herein may be included in a device along with one ormore other cameras such as a wider-field small format camera or atelephoto or narrow angle small format camera, which would for exampleallow the user to select between the different camera formats (e.g.,normal, telephoto or wide-field) when capturing images with the device.In some embodiments, two or more small format cameras as describedherein may be included in a device, for example as front-facing andrear-facing cameras in a mobile device.

Typically, to achieve AF and/or OIS functionality in small form factorcameras, mechanical solutions, such as VCM (voice coil motor) technologythat moves the lens module in relation to the image plane in the Z(optical axis) direction for AF and either by tilting or displacing thelens module in the X and Y (perpendicular to the Z axis) directions forOIS, have been used. FIGS. 1A and 1B illustrate motion of an opticscomponent 102 within an example actuator module 100 that providesmechanical autofocus (AF) and/or optical image stabilization (OIS)functionality for a camera. The actuator module 100 may, for example,include a VCM actuator mechanism. The actuator module 100 may, forexample, be mounted to a substrate 190 that includes a photosensor 150of the camera. The actuator module 100 may provide motion to opticscomponent 102 on the Z (optical) axis and/or in the XY plane. The XYplane motion may, for example, provide optical image stabilization (OIS)by moving the optics component 102 on the X and/or Y axis relative tothe photosensor 150. The Z axis motion may, for example, provide opticalfocusing or autofocus for the camera by moving the optics component 102on the Z axis relative to the photosensor 150.

FIG. 1B illustrates components of an example actuator module 100 thatprovides X, Y and Z motions for an optics component. In this example,the actuator module 100 may include an optics component 102 that iscoupled to an actuator component 104 by upper and/or lower springs 130and 132. The optics component 102 may include a lens barrel 103 thatincludes a stack of lens elements and a lens barrel holder 104. Theobject side of the optics component 102 may be oriented to the top orupper side or surface of the actuator module 100, while the image sideof the optics component 102 may be oriented the bottom or lower side orsurface of the actuator module 100. The actuator component 104 may, forexample, include magnets used in a VCM actuator mechanism. The springs130 and 132 may be flexible to allow motion of the optics component 102on the Z axis relative to the actuator component 104 and photosensor150. The actuator component 104 may be configured to move the opticscomponent 102 and thus the lens barrel 103 on the Z axis within theactuator module 100 and relative to the photosensor 150 to providefocusing or autofocus for the camera. An assembly which includes atleast the optics component 102, actuator component 104, and springs 130and 132 may be suspended within the actuator module 100 on two or moresuspension wires 120. For example, the suspension wires 120 may bemounted to base 108, and the assembly may be suspended on the wires 120at the outer portion of the upper springs 130. The suspension wires 120may be flexible to allow motion of the assembly, and thus of the opticscomponent 102, on the XY axes orthogonal to the Z (optical) axis of theoptics component 102. The actuator component 102 may be configured tomove the optics component 102 and thus the lens barrel 103 on the XYaxes within the actuator module 100 and relative to the photosensor 150to provide optical image stabilization (OIS) for the camera. A cover 112for the assembly may be attached to the base 108 of the actuator module110. The assembled actuator module 100 may, for example, be mounted to asubstrate 190 that includes a photosensor 150 of the camera.

FIG. 2 illustrates a lens module 200 with a fixed master lens and anoptical actuator 210 component that provides autofocus (AF) and/oroptical image stabilization (OIS) functionality for the camera,according to some embodiments. The lens module 200 may include anoptical actuator 210, for example an optical microelectromechanicalsystem (MEMS), and a master lens 212 including one or more refractivelens elements, also referred to as a lens stack. The master lens 212 maybe mounted or affixed inside a holder 204; the holder 204 and masterlens 212 assembly may collectively be referred to as a lens barrel. Theoptical actuator 210 may be located on or within the holder 204 on theobject side of the master lens 212 in front of a first lens of thestack, while the photosensor 212 is located on the image side of thelens stack when the lens barrel is attached to a substrate 290 thatholds the photosensor 250. In some embodiments, the optical actuator 210may include, but is not limited to, a substrate (e.g., a clear glass orplastic substrate), a flexible optical element (e.g., a flexible lens),and an actuator component that is configured to change the shape of theflexible optical element to provide adaptive optical functionality forthe camera without physically moving the lens barrel assembly as is donein the cameras of FIGS. 1A and 1B; the master lens 212 and opticalactuator 210 are fixed and stay stationary in the holder 204, and theassembly is fixed to the substrate 290. An example optical actuator thatmay be used in embodiments is illustrated in FIGS. 6A and 6B. Theoptical functionality provided by the optical actuator 210 may includeautofocus (AF) functionality and/or optical image stabilization (OIS)functionality, for example. The optical actuator 210 may also bereferred to as an SSAF (Solid-State Auto-Focus) and/or SSOIS(Solid-State Optical Image Stabilization) component or module. The AFand/or OIS functionality for the camera is provided by the opticalactuator 210 changing the shape of the flexible optical element toaffect light rays passing from the object field through the flexibleoptical element to the master lens 212, rather than by physically movingthe lens barrel as in conventional AF and/or OIS cameras.

By using an optical actuator 210 that implements SSAF and/or SSOIStechnology to provide AF and/or OIS functionality in small form factorcameras as described herein, there is no longer a requirement tophysically move the lens barrel with respect to the photosensor 250 asis done in the example camera of FIGS. 1A and 1B to achieve AF and/orOIS functionality. This has a significant impact on the X-Y size of thecamera system by reducing the size of the camera in the X-Y dimensionswhen compared to the camera of FIGS. 1A and 1B.

The addition of the optical actuator 212 that provides SSAF and/or SSOISfunctionality to the lens barrel may increase the Z dimension of thelens assembly. However, as the displacement of the lens barrel is nolonger required to achieve AF functionality, a much smaller nominaldistance between the lens barrel and the camera system cover window canbe achieved. This offsets the majority or all of the net increase in theZ dimension due to the addition of the optical actuator 212.

In some embodiments of the lens module 200 as illustrated in FIG. 2,rather than including an aperture stop in the master lens 212, forexample at the first lens element in the lens stack, an aperture stopmay be included in the optical actuator 210, for example between thesubstrate and the flexible optical element of the optical actuator 210.An example optical actuator that includes an aperture stop that may beused in embodiments is illustrated in FIGS. 7A and 7B. Including theaperture stop in the optical actuator 210 rather than in the master lens212 may allow the optical actuator 210 to be smaller in the X-Ydimensions (perpendicular to the optical (Z) axis) than it would be in asimilar camera with the aperture stop located in the master lens 212.This may allow the X-Y dimensions of the camera to be reduced whencompared to a similar camera with the aperture stop located in themaster lens 212. In addition, the smaller optical actuator 212 may beless expensive to manufacture.

FIG. 3 is a cross-sectional illustration of a camera 300 including alens system 320 with a fixed master lens 312 and an optical actuator 310component in which the aperture stop 340 for the camera 300 is locatedwithin the master lens 312, according to some embodiments. Camera 300includes at least a lens system 320 and a photosensor 300. The lenssystem 320 may include a master lens 312 and an optical actuator 310component, for example an optical microelectromechanical system (MEMS).While not shown in FIG. 3, in some embodiments, the master lens 312 maybe fixed within a holder to form a lens barrel; the optical actuator 310may be attached to or mounted within the object side of the lens barrel.In this example, master lens 312 includes five lens elements 301-305with refractive power arranged along an optical axis in order from anobject side to an image side, and an aperture stop 340 for the camera300 located at the first lens element 301 of the master lens 312. Notethat the aperture stop 340 may be located elsewhere within the masterlens 312, for example at or near the front vertex of the first lenselement 301 or between the first lens element 301 and the second lenselement 302. The camera 300 may also, but does not necessarily, includean infrared (IR) filter located between the lens system 320 and thephotosensor 330. The IR filter may, for example, be composed of a glassmaterial. However, other materials may be used. In some embodiments, theIR filter does not have refractive power, and does not affect theeffective focal length of the lens system 320. Further note that thecamera 300 may also include other components than those illustrated anddescribed herein.

The optical actuator 310 may be located on the object side of the masterlens 312 in front of a first lens 301 in the lens stack, while thephotosensor 330 is located on the image side of the master lens 312. Theoptical actuator may 310 include, but is not limited to, a substrate(e.g., a clear glass or plastic substrate), a flexible optical element(e.g., a flexible lens), and an actuator component that is configured todynamically change the shape of the flexible optical element to provideadaptive optical functionality for the camera 300. An example opticalactuator that may be used in camera 300 is illustrated in FIGS. 6A and6B. The optical functionality provided by the optical actuator 310 mayinclude AF functionality and/or OIS functionality, for example. Theoptical actuator 310 may also be referred to as an SSAF and/or SSOIScomponent or module.

Optical characteristics, materials (e.g., plastics or glass), shapes,spacing, and/or sizes of the lens elements in the master lens 312 may beselected to account for the location of the aperture stop 340 within themaster lens 312. For example, the X-Y dimensions of one or more of thelens elements 301-305 in the master lens 312 (e.g., the first three lenselements) may be sized according to the location of the aperture stop340 in the master lens 312 so that the light rays passing through theaperture stop 340 are correctly refracted through the lens elements301-305 to form an image at an image plane on or proximate to thephotosensor 312.

In some embodiments, parameters of the lens elements in the master lens312 including but not limited to lens shape, size, geometry, position,and materials may be selected at least in part to reduce, compensate, orcorrect for lens artifacts and effects including one or more of but notlimited to vignetting, chromatic aberration, the field curvature orPetzval sum, and lens flare. For example, the lens elements 301-305 maybe selected and arranged such that mechanical vignetting is reduced oreliminated.

The lens elements 301-305 of the master lens 312 as shown in FIG. 3 aregiven by way of example and are not intended to be limiting. More orfewer lens elements (e.g., four or six lens elements) may be used in themaster lens 312, and one or more of the lens elements in the master lens312 may be of different shapes, geometries, sizes, or materials withdifferent optical properties (e.g., refractive index or Abbe number).Spacing between the lens elements in the master lens 312 may bedifferent than shown, and various power orders for the lens elements inthe master lens 312 may be used. For example, in the example five lenselement master lens 312 of FIG. 3, the power order, from the first lenselement to the fifth lens element, may be PNNNP, PNPNP, or some otherorder, where P indicates a lens with positive refractive power, and Nrepresents a lens with negative refractive power.

In conventional cameras, an aperture stop for a camera may be includedin the lens stack, for example at the first lens element 301 in themaster lens 312 as shown in the camera 300 of FIG. 3. FIG. 4 is across-sectional illustration of a camera 400 including a lens system 420with a fixed master lens 412 and an optical actuator 412 component inwhich the aperture stop 440 for the camera is instead located in theoptical actuator 412 component, according to some embodiments. Camera400 includes at least a lens system 420 and a photosensor 400. The lenssystem 420 may include a master lens 412 and an optical actuator 410component, for example an optical MEMS. While not shown in FIG. 4, insome embodiments, the master lens 412 may be fixed within a holder toform a lens barrel; the optical actuator 410 may be located at, attachedto, or mounted within the object side of the lens barrel. In thisexample, master lens 412 includes five lens elements 401-405 withrefractive power arranged along an optical axis in order from an objectside to an image side. However, instead of an aperture stop located atthe first lens element of the master lens as shown in the example cameraof FIG. 3, the aperture stop 440 for camera 400 is located at or in theoptical actuator 410 component. The camera 400 may also, but does notnecessarily, include an infrared (IR) filter located between the lenssystem 420 and the photosensor 430. The IR filter may, for example, becomposed of a glass material. However, other materials may be used. Insome embodiments, the IR filter does not have refractive power, and doesnot affect the effective focal length of the lens system 420. Furthernote that the camera 400 may also include other components than thoseillustrated and described herein.

The optical actuator 410 may be located on the object side of the masterlens 412 in front of a first lens 401 in the lens stack, while thephotosensor 430 is located on the image side of the master lens 412. Theoptical actuator 410 may include, but is not limited to, a substrate(e.g., a clear glass or plastic substrate), a flexible optical element(e.g., a flexible lens), and an actuator component that is configured todynamically change the shape of the flexible optical element to provideadaptive optical functionality for the camera 400. An aperture stop 440may be included in the optical actuator 410, for example between thesubstrate and the flexible optical element of the optical actuator 410,on the object side surface of the substrate, or embedded within thesubstrate. An example optical actuator that includes an aperture stopand that may be used in camera 400 is illustrated in FIGS. 7A and 7B.The optical functionality provided by the optical actuator 410 mayinclude AF functionality and/or OIS functionality, for example. Theoptical actuator 410 may also be referred to as an SSAF and/or SSOIScomponent or module.

Including the aperture stop 440 in the optical actuator 410 rather thanin the master lens 412 may allow the optical actuator 410 to be smallerin the X-Y dimensions (perpendicular to the optical (Z) axis) than itwould be in a similar camera with the aperture stop located in themaster lens as shown in FIG. 3. This may allow the X-Y dimensions of thecamera 400 to be reduced when compared to a similar camera with theaperture stop located in the master lens, and may also allow the X-Ydimensions of a cover window for the camera 400 to be reduced. Inaddition, the smaller optical actuator 410 of FIG. 4 may be lessexpensive to manufacture than the larger optical actuator 310 requiredby the camera 300 of FIG. 3.

Optical characteristics, materials (e.g., plastics or glass), shapes,spacing, and/or sizes of the lens elements in the master lens 412 may beselected to account for location of the aperture stop 440 in the opticalactuator 410. For example, the X-Y dimensions of one or more of the lenselements in the master lens 412 (e.g., the first three lens elements401-403) may be increased according to the location of the aperture stop440 in the optical actuator 410 so that the light rays passing throughthe aperture stop 440 are correctly refracted through the lens elementsin the master lens 412 to form an image at an image plane on orproximate to the photosensor 430 of the camera 400.

In some embodiments, one or more parameters of the lens elements in themaster lens 412 including but not limited to lens shape, size, geometry,position, and materials may be selected at least in part to reduce,compensate, or correct for lens artifacts and effects including one ormore of but not limited to vignetting, chromatic aberration, the fieldcurvature or Petzval sum, and lens flare. For example, the lens elements401-405 may be selected and arranged such that mechanical vignetting isreduced or eliminated given the location and size of the aperture stop440 in the optical actuator 410. In particular, lens elements 401 and402, and in some embodiments lens element 403, may be larger in the X-Ydimensions than the respective lens elements in the master lens 312 incamera 300 as shown in FIG. 3 to account for location of the aperturestop 440 in the optical actuator 410. As shown in FIG. 4, the diameterof the lens elements 401, 402, and 403, may be larger than the diameterof the entrance pupil of aperture stop 440 to capture more of theoff-angle, oblique rays at the edge of the entrance pupil to thus insurethat sufficient light is captured at the edges to reduce or eliminatemechanical vignetting in the lens system 420.

The lens elements 401-405 of the master lens 412 as shown in FIG. 4 aregiven by way of example and are not intended to be limiting. More orfewer lens elements (e.g., four or six lens elements) may be used in themaster lens 412, and one or more of the lens elements in the master lens412 may be of different shapes, geometries, sizes, or materials withdifferent optical properties (e.g., refractive index or Abbe number).Spacing between the lens elements in the master lens 412 may bedifferent than shown, and various power orders for the lens elements inthe master lens 412 may be used. For example, in the example five lenselement master lens 412 of FIG. 4, the power order, from the first lenselement to the fifth lens element, may be PNNNP, PNPNP, or some otherorder, where P indicates a lens with positive refractive power, to and Nrepresents a lens with negative refractive power.

FIG. 5 is a cross-sectional illustration of a camera lens assembly ormodule 500 that includes an optical actuator 510 component withintegrated aperture stop 540, a fixed master lens, and an optionalinfrared (IR) filter, according to some embodiments. The camera lensassembly 500 may include a master lens that includes a stack of fivelens elements 501-505 with refractive power arranged along an opticalaxis in order from an object side to an image side and located within amaster lens holder 560 to form a lens barrel. The camera lens assembly500 may also include an optical actuator 510, for example for example anoptical MEMS, that may include, but is not limited to, a substrate(e.g., a clear glass or plastic substrate), a flexible optical element(e.g., a flexible lens), and an actuator component that is configured todynamically change the shape of the flexible optical element to provideadaptive optical functionality such as AF and/or OIS functionality. Anaperture stop 540 may be included in the optical actuator 510, forexample between the substrate and the flexible optical element of theoptical actuator 510. An example optical actuator that includes anaperture stop and that may be used in a camera lens assembly 500 isillustrated in FIGS. 7A and 7B. The optical actuator 510 may be mountedwithin or attached to an optical actuator holder 550 to form an opticalactuator assembly. The optical actuator assembly may be mounted orattached to the front (object side) of the lens barrel. The camera lensassembly 500 may also, but does not necessarily, include an IR filterassembly 570 that may be mounted or attached to the rear (image side) ofthe lens barrel.

Including the aperture stop 540 in the optical actuator 510 rather thanin the master lens may allow the optical actuator 510 to be smaller inthe X-Y dimensions (perpendicular to the optical (Z) axis) than it wouldbe in a similar camera with the aperture stop located in the masterlens. This may allow the X-Y dimensions of the camera lens assembly 500to be reduced when compared to a similar camera lens assembly with theaperture stop located in the master lens and thus requiring a largeroptical actuator, and may also allow the X-Y dimensions of a coverwindow for the camera lens assembly 500 to be reduced. In addition, thesmaller optical actuator 510 may be less expensive to manufacture than alarger optical actuator.

Optical characteristics, materials (e.g., plastics or glass), shapes,spacing, and/or sizes of the lens elements in the lens barrel may beselected to account for location of the aperture stop 540 in the opticalactuator 510. For example, the X-Y dimensions of one or more of the lenselements in the master lens (e.g., the first three lens elements501-503) may be increased according to the location of the aperture stop540 in the optical actuator 510 so that the light rays passing throughthe aperture stop 540 are correctly refracted through the lens elements501-505 in the master lens to form an image at an image plane on orproximate to a photosensor of a camera.

The lens elements 501-505 of the master lens 512 as shown in FIG. 5 aregiven by way of example and are not intended to be limiting. More orfewer lens elements (e.g., four or six lens elements) may be used in themaster lens, and one or more of the lens elements in the master lens maybe of different shapes, geometries, sizes, or materials with differentoptical properties (e.g., refractive index or Abbe number). Spacingbetween the lens elements in the master lens may be different thanshown, and various power orders for the lens elements in the master lensmay be used. For example, in the example five lens element master lensof FIG. 5, the power order, from the first lens element to the fifthlens element, may be PNNNP, PNPNP, or some other order, where Pindicates a lens with positive refractive power, and N represents a lenswith negative refractive power.

FIGS. 6A and 6B illustrate an example optical actuator 610, according tosome embodiments. The optical actuator 610 of FIGS. 6A and 6B may, forexample, be used in a camera 300 as illustrated in FIG. 3. The opticalactuator 610 may include, but is not limited to, a substrate 612 (e.g.,a clear glass or plastic substrate), a flexible optical element 616(e.g., a flexible lens), and an actuator 614 component that isconfigured to change the shape of the flexible optical element 616 toprovide adaptive optical functionality for a camera. The flexibleoptical element 616 may include a flexible membrane 617 and a fluid(e.g., optical oil) in one or more cavities between the flexiblemembrane 618 and the surface of the substrate 612. For example, tochange the shape of the flexible optical element 616, the actuator 614component may add or remove fluid 618 from the cavity(s). The opticalfunctionality provided by the optical actuator 610 may include autofocus(AF) functionality and/or optical image stabilization (OIS)functionality, for example. While FIG. 6B shows the flexible opticalelement 616 with a curved membrane 617, in some embodiments the flexibleoptical element 616 may be made substantially flat to focus at infinity.While FIG. 6B shows the substrate 612 as rectangular or square, thesubstrate 612 may be other shapes, for example round.

FIGS. 7A and 7B illustrate an example optical actuator component thatincludes an aperture stop, according to some embodiments. The opticalactuator 710 of FIGS. 7A and 7B may, for example, be used in a camera400 as illustrated in FIG. 4 or camera lens assembly 500 as illustratedin FIG. 5. The optical actuator 710 may include, but is not limited to,a substrate 712 (e.g., a clear glass or plastic substrate), a flexibleoptical element 716 (e.g., a flexible lens), and an actuator 714component that is configured to change the shape of the flexible opticalelement 716 to provide adaptive optical functionality for a camera. Theflexible optical element 716 may include a flexible membrane 717 and afluid (e.g., optical oil) in one or more cavities between the flexiblemembrane 718 and the surface of the substrate 712. For example, tochange the shape of the flexible optical element 716, the actuator 714component may add or remove fluid 718 from the cavity(s). The opticalfunctionality provided by the optical actuator 710 may include autofocus(AF) functionality and/or optical image stabilization (OIS)functionality, for example. While FIG. 7B shows the flexible opticalelement 716 with a curved membrane 717, in some embodiments the flexibleoptical element 716 may be made substantially flat to focus at infinity.While FIG. 7B shows the substrate 712 as rectangular or square, thesubstrate 712 may be other shapes, for example round.

An aperture stop 740 may be included in the optical actuator 710, forexample between the substrate 712 and the flexible optical element 716of the optical actuator 710. Including the aperture stop 740 in theoptical actuator 710 rather than in the master lens of the camera mayallow the optical actuator 710 to be smaller in the X-Y dimensions(perpendicular to the optical (Z) axis) than the optical actuator 610shown in FIGS. 6A and 6B. This may allow the X-Y dimensions of thecamera lens assembly and the camera to be reduced when compared to acamera lens assembly and camera that uses the optical actuator 610 asillustrated in FIGS. 6A and 6B, and may also allow the X-Y dimensions ofa cover window for the camera lens assembly to be reduced. In addition,the smaller optical actuator 710 of FIGS. 7A and 7B may be lessexpensive to manufacture than the larger optical actuator 610 shown inFIGS. 6A and 6B.

The aperture stop 740 may be included in the optical actuator 710 in anyof various ways, and at other locations than between the substrate 712and the flexible optical element 716. For example, the aperture stop 740may be located on the object side of the substrate 712, or within thesubstrate (for example, between two panes of glass). The aperture stopmay, for example, be an opaque substance applied to the image or objectside surface of the substrate 712, or a thin membrane or sheet of opaquematerial attached to the image or object side surface of the substrate712, or between two panes of glass of the substrate 712.

FIG. 8 is a high-level flowchart of a method for capturing images usinga camera as illustrated in FIG. 4, according to some embodiments. Asindicated at 800, light from an object field in front of the camera isreceived at an optical actuator of the camera and passes through anaperture stop of the optical actuator to a flexible optical element ofthe optical actuator. FIGS. 7A and 7B illustrate an example opticalactuator that may be used. As indicated at 802, the light is refractedby the flexible optical element of the optical actuator to a first lenselement of a master lens of the camera. The master lens may includemultiple (e.g., five) lens elements arranged along an optical axis ofthe camera from the first lens element to a last lens element. FIGS. 4and 5 show examples of master lenses that may be used. The shape of theflexible optical element may be dynamically changed by the opticalactuator to provide AF and/or OIS functionality for the camera. Asindicated at 804, the light is refracted by the lens elements in themaster lens to form an image at an image plane at or near the surface ofa photosensor of the camera. As indicated at 806, the image is capturedby the photosensor. While not shown, in some embodiments, the light maypass through an infrared filter that may for example be located betweenthe last lens element in the master lens and the photosensor.

FIG. 9 shows components of an example small form factor camera thatincludes a camera lens assembly as illustrated in FIG. 5 and illustratesa method for assembling the camera, according to some embodiments. FIG.9 shows side and top views of components of the camera 900. In someembodiments, a small form factor camera 900 may include, but is notlimited to, a lens barrel 912 including a stack of lenses that form amaster lens for the camera 900, an optical actuator 910 that, forexample, provides optical AF and/or OIS functionality for the camera900, an IR filter assembly 970, a photosensor 950 mounted to a substrate990 in a device, an outer cover 906 for the camera lens assembly 906,and a cover window 902 for the camera 900. In some embodiments, toassemble the camera 900, the lens elements are inserted into a lensstack holder to assemble the lens barrel 912 (1), the IR filter assembly970 and optical actuator 910 components are attached to the lens barrel912 to form the camera lens assembly ((2) and (3)), the camera lensassembly is inserted in the outer cover 906 (4), the cover window 902 isattached to the outer cover 906 (5), and the assembled camera body isthen attached to the substrate 990 over the photosensor 950 (6).

Note that the order of the assembly steps (1) through (6) is notintended to be limiting. For example, the components may be assembled inother orders. Also, there may be more or fewer components, and there maybe may be more or fewer steps in the assembly process. For example,steps (2) and (3) may be reversed, or may be performed substantiallysimultaneously. As another example, the camera lens assembly may beattached to the substrate 990 before the cover 906 is installed.

In some embodiments, at least some of the components of the camera 900may be manufactured and/or assembled by different entities (e.g.,vendors for the different components) at different locations, andmounting the assembly to the substrate 990 may be performed by an entityat a facility that assembles a device (e.g., a mobile device) thatincludes the small form factor camera 900. For example, the lens barrel912 may be assembled at one facility, the optical actuator 910 may beassembled at another facility, and the components may be assembled toform the camera 900 at yet another facility.

The entity that assembles the lens barrel 912 typically tests the lensstack in the barrel 912 once assembled to insure the opticalcharacteristics and quality of the master lens meets specifications.However, to test the optical characteristics and quality of a cameralens, an aperture stop is required. Since the aperture stop is includedin the optical actuator 910 and not in the lens stack and the opticalactuator 910 is not available, an optical actuator simulator device thatmatches the characteristics of the optical actuator 910 (e.g., diameterand distance from the first lens of the lens stack in the lens barrel,optical power of the lens element of the optical actuator 910, if any)may be used to test the assembled lens barrel 912. In some embodiments,the optical actuator 910 may have zero (0) optical power when focused atinfinity, which would simplify the testing of the assembled lens barrel912 with the optical actuator simulator.

The entity that manufactures and/or assembles the optical actuator 910typically tests optical actuator 910 to insure that the optical actuator910 is compatible with the master lens. For example, a wavefrontanalysis machine or the like may be used to test the optical actuator.

In some embodiments, at step (6), during the process of attaching theassembled camera body to the substrate 990 over the photosensor 950, atechnique (e.g., an active alignment process) may be used to insure thatthe alignment and relative position of the camera lens assembly to thephotosensor 950 in the X, Y, and/or Z dimensions is correct according tospecifications and within tolerances of the camera, and to maximizecamera system performance and yield. In some embodiments, the activealignment process involves setting the optical actuator 910 to itsnominal infinity voltage (e.g., 20C voltage), doing Z alignment of thephotosensor 950 to find optimal focus, and then performing X and Y tiltof the image plane to find optimal field performance. In someembodiments, an additional step can be performed during the activealignment process to optimize the optical actuator 910 voltage to ensurethat the image field curvature is as flat as possible for the infinity20C case. In some embodiments, the completed system may be tested, forexample using one or more spatial frequency response (SFR) techniques.

FIG. 9B shows an example small form factor camera that includes a cameralens assembly as illustrated in FIG. 5 and provides example dimensionsand optical characteristics for the camera, according to someembodiments. The measurements are given in millimeters (mm). Themeasurements and optical characteristics are not intended to belimiting.

As shown in the example camera of FIG. 9B, the optical actuator 910 maybe @0.2 mm thick. X-Y dimensions of the camera lens assembly may bewithin a range of 4.9-5.4 mm. X-Y dimensions of the camera body may bewithin a range of 5.4-7.7 mm. Z (height) dimension of the camera bodymay be within a range of 4.5-5.5 mm. Thickness of the cover window maybe @0.2 mm. Thickness of the optical actuator 910 may be @0.2 mm, forexample within a range of 1.9 to 2.1 mm. X-Y dimensions of the opticalactuator 910 may be within a range of 3.5-5.0 mm. The angle through theentrance pupil (the aperture stop in the optical actuator 910) withvertex at the front vertex of the first lens in the master lens may be75-80°, for example 77°. The diameter of the entrance pupil (D) of theaperture stop 910 may be within a range of 1.37 to 1.47 mm, for example1.42 mm. Total track length (TTL) of the master lens may be @4.0; TTLincluding the optical actuator 910 may be @4.6. Note that the TTL of themaster lens and/or master lens with optical actuator may be shorter orlonger than the example TTLs that are given; for example, TTL of themaster lens may be within a range of 3.5-4.5 mm (e.g., 4.0 mm), and TTLof the master lens with optical actuator may be within a range of3.9-5.1 mm (e.g., 4.6 mm). The lens system of the example camera 900 mayhave paraxial focal length (f) of @2.8 (e.g., within a range of 2.8 to2.9 mm, e.g., 2.85), and an f-number (focal ratio) of @2.0 (e.g., withina range of 1.9-2.1). The f-number or focal ratio of a lens system is theratio (f/D) of the lens system's focal length (f) to the diameter of theentrance pupil (D) of the aperture stop. Telephoto ratio (TTL/f) of theexample camera 900 is @2.3. Note that the lens elements in the lenssystem may be selected to provide other f-numbers and/or telephotoratios, for example various f-numbers within the range 1.8-10.0, and/ortelephoto ratios lower or higher than 2.3, including telephoto ratiosthat are less than or equal to 1.0.

Example Computing Device

FIG. 10 illustrates an example computing device, referred to as computersystem 2000, that may include or host embodiments of the camera asillustrated in FIGS. 2 through 9B. In addition, computer system 2000 mayimplement methods for controlling operations of the camera and/or forperforming image processing of images captured with the camera. Indifferent embodiments, computer system 2000 may be any of various typesof devices, including, but not limited to, a personal computer system,desktop computer, laptop, notebook, tablet or pad device, slate, ornetbook computer, mainframe computer system, handheld computer,workstation, network computer, a camera, a set top box, a mobile device,a wireless phone, a smartphone, a consumer device, video game console,handheld video game device, application server, storage device, atelevision, a video recording device, a peripheral device such as aswitch, modem, router, or in general any type of computing or electronicdevice.

In the illustrated embodiment, computer system 2000 includes one or moreprocessors 2010 coupled to a system memory 2020 via an input/output(I/O) interface 2030. Computer system 2000 further includes a networkinterface 2040 coupled to I/O interface 2030, and one or moreinput/output devices 2050, such as cursor control device 2060, keyboard2070, and display(s) 2080. Computer system 2000 may also include one ormore cameras 2090, for example one or more cameras as described abovewith respect to FIGS. 2 through 9B, which may also be coupled to I/Ointerface 2030, or one or more cameras as described above with respectto FIGS. 2 through 9B along with one or more other cameras such aswide-field and/or telephoto cameras.

In various embodiments, computer system 2000 may be a uniprocessorsystem including one processor 2010, or a multiprocessor systemincluding several processors 2010 (e.g., two, four, eight, or anothersuitable number). Processors 2010 may be any suitable processor capableof executing instructions. For example, in various embodimentsprocessors 2010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 2010 may commonly,but not necessarily, implement the same ISA.

System memory 2020 may be configured to store program instructions 2022and/or data 2032 accessible by processor 2010. In various embodiments,system memory 2020 may be implemented using any suitable memorytechnology, such as static random access memory (SRAM), synchronousdynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type ofmemory. In the illustrated embodiment, program instructions 2022 may beconfigured to implement various interfaces, methods and/or data forcontrolling operations of camera 2090 and for capturing and processingimages with integrated camera 2090 or other methods or data, for exampleinterfaces and methods for capturing, displaying, processing, andstoring images captured with camera 2090. In some embodiments, programinstructions and/or data may be received, sent or stored upon differenttypes of computer-accessible media or on similar media separate fromsystem memory 2020 or computer system 2000.

In one embodiment, I/O interface 2030 may be configured to coordinateI/O traffic between processor 2010, system memory 2020, and anyperipheral devices in the device, including network interface 2040 orother peripheral interfaces, such as input/output devices 2050. In someembodiments, I/O interface 2030 may perform any necessary protocol,timing or other data transformations to convert data signals from onecomponent (e.g., system memory 2020) into a format suitable for use byanother component (e.g., processor 2010). In some embodiments, I/Ointerface 2030 may include support for devices attached through varioustypes of peripheral buses, such as a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some embodiments, the function of I/Ointerface 2030 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someembodiments some or all of the functionality of I/O interface 2030, suchas an interface to system memory 2020, may be incorporated directly intoprocessor 2010.

Network interface 2040 may be configured to allow data to be exchangedbetween computer system 2000 and other devices attached to a network2085 (e.g., carrier or agent devices) or between nodes of computersystem 2000. Network 2085 may in various embodiments include one or morenetworks including but not limited to Local Area Networks (LANs) (e.g.,an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., theInternet), wireless data networks, some other electronic data network,or some combination thereof. In various embodiments, network interface2040 may support communication via wired or wireless general datanetworks, such as any suitable type of Ethernet network, for example;via telecommunications/telephony networks such as analog voice networksor digital fiber communications networks; via storage area networks suchas Fibre Channel SANs, or via any other suitable type of network and/orprotocol.

Input/output devices 2050 may, in some embodiments, include one or moredisplay terminals, keyboards, keypads, touchpads, scanning devices,voice or optical recognition devices, or any other devices suitable forentering or accessing data by computer system 2000. Multipleinput/output devices 2050 may be present in computer system 2000 or maybe distributed on various nodes of computer system 2000. In someembodiments, similar input/output devices may be separate from computersystem 2000 and may interact with one or more nodes of computer system2000 through a wired or wireless connection, such as over networkinterface 2040.

As shown in FIG. 10, memory 2020 may include program instructions 2022,which may be processor-executable to implement any element or action tosupport integrated camera 2090, including but not limited to imageprocessing software and interface software for controlling camera 2090.In some embodiments, images captured by camera 2090 may be stored tomemory 2020. In addition, metadata for images captured by camera 2090may be stored to memory 2020.

Those skilled in the art will appreciate that computer system 2000 ismerely illustrative and is not intended to limit the scope ofembodiments. In particular, the computer system and devices may includeany combination of hardware or software that can perform the indicatedfunctions, including computers, network devices, Internet appliances,PDAs, wireless phones, pagers, video or still cameras, etc. Computersystem 2000 may also be connected to other devices that are notillustrated, or instead may operate as a stand-alone system. Inaddition, the functionality provided by the illustrated components mayin some embodiments be combined in fewer components or distributed inadditional components. Similarly, in some embodiments, the functionalityof some of the illustrated components may not be provided and/or otheradditional functionality may be available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or on storage while beingused, these items or portions of them may be transferred between memoryand other storage devices for purposes of memory management and dataintegrity. Alternatively, in other embodiments some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated computer system 2000 via inter-computercommunication. Some or all of the system components or data structuresmay also be stored (e.g., as instructions or structured data) on acomputer-accessible medium or a portable article to be read by anappropriate drive, various examples of which are described above. Insome embodiments, instructions stored on a computer-accessible mediumseparate from computer system 2000 may be transmitted to computer system2000 via transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as a network and/or a wireless link. Various embodiments mayfurther include receiving, sending or storing instructions and/or dataimplemented in accordance with the foregoing description upon acomputer-accessible medium. Generally speaking, a computer-accessiblemedium may include a non-transitory, computer-readable storage medium ormemory medium such as magnetic or optical media, e.g., disk orDVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR,RDRAM, SRAM, etc.), ROM, etc. In some embodiments, a computer-accessiblemedium may include transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The methods described herein may be implemented in software, hardware,or a combination thereof, in different embodiments. In addition, theorder of the blocks of the methods may be changed, and various elementsmay be added, reordered, combined, omitted, modified, etc. Variousmodifications and changes may be made as would be obvious to a personskilled in the art having the benefit of this disclosure. The variousembodiments described herein are meant to be illustrative and notlimiting. Many variations, modifications, additions, and improvementsare possible. Accordingly, plural instances may be provided forcomponents described herein as a single instance. Boundaries betweenvarious components, operations and data stores are somewhat arbitrary,and particular operations are illustrated in the context of specificillustrative configurations. Other allocations of functionality areenvisioned and may fall within the scope of claims that follow. Finally,structures and functionality presented as discrete components in theexample configurations may be implemented as a combined structure orcomponent. These and other variations, modifications, additions, andimprovements may fall within the scope of embodiments as defined in theclaims that follow.

What is claimed is:
 1. A lens system, comprising: a master lenscomprising a plurality of refractive lens elements arranged along anoptical axis of the lens system; and an optical actuator located on theoptical axis of the lens system on an object side of the master lens andconfigured to provide one or more optical functionalities for a camerawithout moving the master lens, wherein the optical functionalitiesinclude one or more of autofocus or optical image stabilization; whereinthe optical actuator includes an aperture stop for the lens system. 2.The lens system as recited in claim 1, wherein the optical actuatorcomprises: a substrate at least partially composed of a clear material;the aperture stop; a flexible optical element attached to the substrate;and one or more actuator components configured to change a shape of theflexible optical element to provide the one or more opticalfunctionalities for the camera.
 3. The lens system as recited in claim2, wherein the flexible optical element is attached to an image sidesurface of the substrate and is substantially centered on the opticalaxis of the lens system.
 4. The lens system as recited in claim 2,wherein the aperture stop is located between the substrate and theflexible optical element.
 5. The lens system as recited in claim 2,wherein the aperture stop is located on an image side surface of thesubstrate, on the object side surface of the substrate, or within thesubstrate, and wherein the aperture stop comprises an opaque substanceor a sheet of opaque material.
 6. The lens system as recited in claim 2,wherein the flexible optical element includes a flexible lens comprisinga flexible membrane and a fluid-filled cavity, wherein the one or moreactuator components add fluid to or remove fluid from the cavity tochange the shape of the flexible lens.
 7. The lens system as recited inclaim 1, wherein the master lens includes five lens elements withrefractive power.
 8. The lens system as recited in claim 1, whereindiameter of an entrance pupil of the aperture stop is within a range of1.37 millimeters to 1.47 millimeters.
 9. The lens system as recited inclaim 1, wherein X-Y dimensions of the optical actuator are within arange of 3.5 millimeters to 5.0 millimeters, and wherein thickness onthe optical axis of the optical actuator is within a range of 1.9 to 2.1mm.
 10. The lens system as recited in claim 1, wherein total tracklength of the lens system is within a range of 3.9 millimeters to 5.1millimeters.
 11. The lens system as recited in claim 1, wherein focallength f of the lens system is within a range of 2.8 millimeters to 2.9millimeters.
 12. The lens system as recited in claim 1, wherein focalratio of the lens system is within a range of 1.9 to 2.1 millimeters.13. The lens system as recited in claim 1, wherein diameters of a first,second, and third lens elements on the object side of the master lensare larger than diameter of an entrance pupil of the aperture stop toreduce or eliminate mechanical vignetting in the lens system.
 14. Acamera, comprising: a photosensor configured to capture light projectedonto a surface of the photosensor; and a lens system configured torefract light from an object field located in front of the camera toform an image of a scene at an image plane at or near the surface of thephotosensor, wherein the lens system comprises: a master lens comprisinga plurality of refractive lens elements arranged along an optical axisof the camera, wherein the master lens is fixed within a body of thecamera; and an optical actuator located on the optical axis of thecamera on the object side of the master lens and configured to provideone or more optical functionalities for a camera without moving themaster lens, wherein the optical functionalities include one or more ofautofocus or optical image stabilization, wherein the optical actuatorincludes an aperture stop for the camera.
 15. The camera as recited inclaim 14, further comprising an infrared filter located between themaster lens and the photosensor.
 16. The camera as recited in claim 14,wherein the optical actuator comprises: a substrate composed of a clearmaterial; the aperture stop; a flexible optical element attached to thesubstrate; and one or more actuator components configured to change ashape of the flexible optical element to provide the one or more opticalfunctionalities for the camera.
 17. The camera as recited in claim 16,wherein the aperture stop is located on a surface of the substrate andbetween the substrate and the flexible optical element.
 18. The cameraas recited in claim 14, wherein total track length of the camera iswithin a range of 3.9 millimeters to 5.1 millimeters, diameter of theentrance pupil of the aperture stop is within a range of 1.37millimeters to 1.47 millimeters, focal length f of the camera is withina range of 2.8 millimeters to 2.9 millimeters, and focal ratio of thecamera within a range of 1.9 to 2.1 millimeters.
 19. A device,comprising: one or more processors; one or more cameras; and a memorycomprising program instructions executable by at least one of the one ormore processors to control operations of the one or more cameras;wherein at least one of the one or more cameras is a camera comprising:a photosensor configured to capture light projected onto a surface ofthe photosensor; and a lens system configured to refract light from anobject field located in front of the camera to form an image of a sceneat an image plane at or near the surface of the photosensor, wherein thelens system comprises: a master lens comprising a plurality ofrefractive lens elements arranged along an optical axis of the camera,wherein the master lens is fixed within a body of the camera; and anoptical actuator located on the optical axis of the camera on the objectside of the master lens and configured to provide one or more opticalfunctionalities for a camera without moving the master lens, wherein theoptical functionalities include one or more of autofocus or opticalimage stabilization, wherein the optical actuator includes an aperturestop for the camera.
 20. The device as recited in claim 19, wherein theoptical actuator comprises: a substrate composed of a clear material;the aperture stop; a flexible optical element attached to the substrate;and one or more actuator components configured to change a shape of theflexible optical element to provide the one or more opticalfunctionalities for the camera; wherein the aperture stop is located ona surface of the substrate and between the substrate and the flexibleoptical element.